The present invention relates generally to a new and novel method and structure for making caster and pinion angle adjustment for motor vehicle axle assemblies. More particularly, the present invention relates to a method and structure for making caster and pinion angle adjustment for motor vehicle axle assemblies where the motor vehicle axle assemblies have only minimal capability for caster and pinion angle adjustment as originally manufactured including formed adjuster brackets which are attached to an appropriately modified axle mounting bracket. The formed adjuster brackets act as a reaction point for actuating a cam bolt which positions a mounting member at a desired location in an adjustment slot.
Motor vehicles, such as four-wheel drive trucks and automobiles, often employ a solid axle structure arrangement in which a tube yoke is fixedly attached to the solid axle. Pivoting members, such as ball joints, are typically positioned between the tube yoke and a steering knuckle which, in turn, carry a spindle upon which a motor vehicle wheel is mounted for rotation therewith. By incorporating an axle design where the common rotational axis of the pivoting members is positioned other than vertical, when mounted in a vehicle, caster angle is thereby introduced into the suspension system. Pinion angle is determined by the relationship of the axle's center section relative to the axle's vehicle attachment points. Generally beam-type steering axles have an unalterable relationship between caster angle and pinion angle. Any effort that results in a change to one characteristic will also cause a change in the other. Axles that do not incorporate steering capacity have no caster, but retain the pinion angle characteristic only.
Caster gives the motor vehicle steering wheel the ability to return to center after a turn. An increase in caster generally results in an increase in steering effort. In conjunction with other suspension system geometry factors, proper caster contributes to a reduction in wheel shimmy.
A vehicle with improperly adjusted caster will lose some of its natural tracking ability which is commonly referred to as a loss of "on center feel." The steering wheel may not stay centered when hand pressure is released. Improperly adjusted caster may cause a lead condition where the vehicle pulls to one direction. Improper caster adjustment may also be responsible for excessive steering effort.
Caster adjustments are important in providing proper motor vehicle directional stability, handling characteristics and safety. Pinion angle adjustment is important for optimum driveline joint life, and for minimization of noise, vibration and harshness (NVH) related customer complaints.
Thus, motor vehicle caster or pinion angle misadjustment can result in customer dissatisfaction through poor vehicle handling, increased levels of vibration or noise within the passenger compartment.
Dimensional variation is inherent in the manufacturing processes commonly utilized to fabricate axles, vehicle bodies, and the associated attachment-mounting members. The result is that caster and pinion angles will vary from vehicle to vehicle. These dimensional variations may, in total, deviate sufficiently from ideal values that adjustment is desirable. An additional need for caster and pinion angle adjustment occurs for vehicles originally produced with acceptable caster and pinion angles which have subsequently been detrimentally altered through impact or collision.
Many traditional beam-type axles are manufactured with fixed caster and pinion angles. Fixed settings have the advantage of being the simplest and lowest cost to manufacture. Having a method and structure to provide caster and pinion angle adjustment for vehicles originally manufactured without such a provision, is desirable. Economically, only the vehicles actually needing adjustment would be modified. This avoids the unnecessary manufacturing operations and increased costs necessary to provide adjustment capability for every originally manufactured axle. The majority of all axles produced may never actually require such adjustment.
Various methods and structures have been used in an attempt to provide for motor vehicle caster and pinion angle adjustment. For example, in some instances, slotted brackets with welded in place cam bolt reaction members have been used. This methodology is costly due to the additional stamping required for the reaction members, followed by extra fabrication operations to locate and weld these members in place on one hundred percent of the original equipment brackets. Other prior art caster and pinion angle adjustment arrangements have utilized cam bolt reaction points created by raising the parent material of the bracket during the bracket forming operation. This arrangement requires that the final hole or slot position be determined at the time of bracket manufacturing. This substantially reduces the ability to control other axle characteristics which are achievable only by creating the mounting hole after the bracket is welded in place on the axle tube assembly. Maintenance of the forming dies and dimensional control of the raised material becomes more critical. Such prior art methods leave opportunities for reduction in cost and complexity.
A preferred embodiment of the present invention is, therefor, directed to a method and structure for making caster and pinion angle adjustment to motor vehicle axle assemblies which have only minimal capability for caster and pinion angle adjustment as originally manufactured including formed adjuster brackets which are attached to an appropriately modified axle mounting bracket. The formed adjuster brackets act as a reaction point for actuating a cam bolt which positions a mounting member at a desired location in an adjustment slot.
Accordingly, the method and structure for making caster and pinion angle adjustment to motor vehicle axle assemblies in accordance with the present invention provides a simple, cost-effective arrangement for adjusting caster and pinion angle in motor vehicle axle assemblies.
Other advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.